Study on corrosion and mechanical properties of railway steel in industrial atmosphere

Abstract

Salt spray tests were conducted to simulate the corrosion behavior of Q345, Q370, and Q500qENH steels under industrial atmospheric conditions. The experiments included five corrosion cycles: 2, 4, 8, 18, and 30 days. The weight loss of steel under various corrosion cycles was calculated using the corrosion weight loss method. Based on the experimental data, the corrosion rate of steel was analyzed to investigate the corrosion kinetics. The corrosion morphology and elemental content of the rust layer were analyzed using scanning electron microscopy (SEM) and an energy-dispersive spectrometer (EDS). The composition of the rust layer was analyzed by X-ray diffraction (XRD) under different corrosion durations. The surface roughness of the steel, after rust removal, was measured with a confocal scanning microscope. Additionally, the Tafel curve and electrochemical impedance of the rust layer were evaluated using electrochemical methods. Finally, the relationship between corrosion time and degradation of mechanical properties of steel sheet was investigated by static stretching of steel sheet with varying corrosion periods. The results indicate that the corrosion rates of Q345, Q370, and Q500qENH in an industrial atmospheric environment consistently decrease as corrosion time increases. This reduction in corrosion rate is primarily due to the increased presence of structurally dense corrosion product α-FeOOH. The corrosion rate of Q500qENH is comparable to that of Q345 and Q370 during the early stage; however, it is significantly lower than the rates of the other two in the later stage. As the corrosion time increases, both the area and depth of corrosion pits on the surface of the three types of steel continue to expand. Ultimately, a relationship between mechanical parameters and corrosion age is established, revealing a linear decrease.